# A067710 (b-file synthesized from sequence entry) 1 1 2 5 3 17 4 110 5 394 6 4884 7 18108 8 294384 9 2054736 10 27986400 11 160460640 12 5733590400 13 26029779840 14 727452230400 15 11030096851200 16 223495556659200 17 1579093018675200 18 83918534992588800 19 553210247226470400 20 32584767906539520000 21 463473994611898368000 22 10352822932220719104000